In, for example, DE-27 15 414 and U.S. Pat. No. 3,978,852, electric toothbrush arrangements are provided wherein a toothbrush includes a drive shaft driven in a drive unit, for example, a handle housing. The rotary motion of the drive shaft is converted to a cyclic linear motion in the housing itself in order to move a toothbrush head mounted in the handle housing back and forth as a unit.
In German Utility Model DE-G 89 11 427.2 an electric toothbrush is proposed in which a drive shaft projects through the head of the brush and moves a toothbrush mounted endwise back and forth with a cyclic linear motion derived from the shaft. The rotary axis of the cyclic linear motion runs parallel to the rotational axis of the drive shaft.
An electric toothbrush according to European Patent Application No. 0 173 114, with the present patent application being a continuation and improvement on said European patent application.
As in the above-mentioned European patent application, it is important that the various tooth surfaces be cleaned equally well by a cleaning device. Therefore it is important that, in particular the inner, that is, facing the oral cavity, as well as the gums, and the outer tooth surfaces, that is the tooth surfaces facing the cheeks of the user, and the gums themselves, all be cleaned equally, as well as possible. It is also important that the best possible local cleaning pressure be provided at all points to be cleaned. Finally, it is important that the cleaning elements perform optimum movements, that is, movement directed from the gum outward and toward the crown of the tooth as coaxially as possible with respect to the tooth, and not in the opposite direction.
In the above-mentioned European Patent Application No. 0 173 114, which is an integral component of the present application, the method for cleaning the teeth by an electric toothbrush is especially important for the present application, which states that it is important that cleaning be performed simultaneously on at least two sides of the tooth. The method defined according to European Patent Application No. 0 173 114 and important to the invention as well as the device features of the electric toothbrush thus defined, in combination with the features of the invention defined below for the present invention, constitute features of the present patent application that are essential to the invention.
In EP-A-0 173 114, the various motions in a electric toothbrush defined according to the invention are executed primarily with pneumatically or hydraulically operable drive elements. Although the hydraulically or pneumatically operable drive elements have proven themselves, one goal of the present invention is to refine the drive mechanism further and to simplify it in order firstly to increase further the operational safety of electric toothbrushes, to reduce manufacturing costs, and finally to permit a smaller design for the cleaning heads.